Scotland Yard said a 23-year-old man was arrested in Croydon on Sunday on suspicion of attempted murder, while a 26-year-old man and 17-year-old girl were detained on suspicion of attempted murder and violent disorder.

Five other people are still being questioned by detectives while a sixth, a woman of 20, was released without charge.

The group – three men of 20, one of 24 and a 24-year-old woman – are also being held on suspicion of attempted murder and violent disorder.

The incident has drawn widespread condemnation, with Tory minister Gavin Barwell describing the attackers as “scum”.

Absolutely shocked at attack on young Kurdish asylum seeker, who came here searching for safety. I fervently hope he makes a full recovery.

“Then when they heard sirens they started to go. People that were there, witnesses, because they couldn’t do anything against a group of 30 people, they had to wait until they moved off and that’s when they managed to help him.

“That’s eventually when the ambulance and police (arrived), and that was it.”

Detectives are investigating whether some of those involved had been drinking in The Goat pub nearby.

Managers at the pub said they were “saddened” to hear of the incident, adding: “We do not in any way condone such action and we will do anything within our powers to help police to bring those that carried out this act to book. To the victim, we pray for his speedy recovery.”

Chief Superintendent Jeff Boothe, Croydon’s borough commander, called it a “savage attack” and said it was only the intervention of passers-by and the arrival of police that stopped it being worse.

London Mayor Sadiq Khan also condemned the attack, saying hate crime “has no place in London, Britain or anywhere else”, while the Refugee Council said it was “disgusted” by the assault.

Anyone with information about the attack should call police on 101 or Crimestoppers on 0800 555 111.